Oldham completed back to back wins over Notts County to reach the second round of the Worthington Cup.
Having beaten the Magpies 3-1 at Meadow Lane in Saturday's League fixture they again carved out plenty of chances and converted three of them through Chris Killen, Tony Carss and Clyde Wijnhard.
But Notts gave them a rougher ride in the re-match and Latics boss Iain Dowie admitted: "We got through despite not playing very well.
"We should have scored six or seven with the opportunities we had but we weren't solid enough at the back."
County manager Bill Dearden, a former Oldham player, added: "We played a lot better than on Saturday but switched off at important times which cost us at least two of the goals.
"That's six we've conceded in a week and it can't go on. I can't buy players so we'll just have to work with what we've got."
Oldham goalkeeper David Miskelly, in his first game of the season, was soon called into action with one of several fine saves.
Danny Allsopp looked sure to score until Miskelly stuck out a leg to divert his fifth minute shot wide.
Oldham struck in the tenth minute as Julian Baudet met a David Eyres free-kick and Killen turned in the rebound when the first header was saved.
Five minutes later, Richard Liburd crossed from the left and Mark Stallard equalised with a neat finish from eight yards.
Both sides had chances before Oldham struck in first-half injury time. Midfielder Carss played a one-two with Killen before charging into the area and hitting a shot which was deflected into the bottom corner.
The home side should have extended their lead before Notts equalised after 75 minutes when substitute Paul Heffernan headed in at the far post from a delightful cross by the outstanding Darren Caskey.
But Oldham made sure of their place int he draw ten minutes from time when John Sheridan took a quick free-kick and Wijnhard tapped in Josh Low 's cross from the right